Method for releasing a safety device in a motor vehicle in the event of an overturn

ABSTRACT

Method for the triggering of a safety device in a motor vehicle in a rollover process, wherein the rotation rate signals ω generated by a rotation rate sensor are evaluated for the recognition of the rollover process of the motor vehicle about one of its axes. In that regard, predominantly roll bars, side airbags, and belt tensioners come into consideration as safety devices. The object of the invention consists in presenting a method for the triggering of a safety device, without, however, simultaneously suffering an impairment of the safe and reliable recognizing of a tip-over. According to the invention, low-pass filtered rotation rate signals are compared with an adjustable threshold value, whereby this threshold value is generated dependent on the integrated rotation rate signal. In that regard, the low-pass filtering occurs with a limit frequency, with which the signal components of the rotation rate signal characteristic for a rollover process remain unfiltered.

The invention relates to a method for the triggering of a safety devicein a motor vehicle in a rollover process, in which the rotation ratesignals produced by a rotation rate sensor are evaluated for therecognition of a tip-over of the motor vehicle about one of its axes. Inthat regard, predominantly roll bars, side airbags, and belt tensionerscome into consideration as safety devices.

For the recognition of a tip-over of a motor vehicle, for example withrespect to its longitudinal axis (x-axis), it is known for this purposeto evaluate the rotation rate signals produced by a rotation rate sensor(gyro sensor). A corresponding evaluating method is, for example, knownfrom the DE 100 25 259 A1, in which the method begins and proceeds froma theoretical tip-over characteristic curve in the form of a ω-α-graphadapted to the respective vehicle. This ω-α-graph is approximatedthrough low-pass filter functions with certain limit frequencies andtrigger thresholds respectively adapted to the tip-over scenarios thatare to be detected. The rotation rate signals are processed andevaluated by these low-pass filter functions, in order to bring about atriggering of a safety device if applicable. It is disadvantageous inthis known method, however, that voluminous data material must beavailable for the developing and for the adaptation of this triggeringalgorithm to a special vehicle type.

A different method for the detection of rollover processes is known fromthe DE 100 25 260 A1, in which, for the calculation of the currentactual tilt angle of the vehicle, the value of the integrated rotationrate signal is added to the initial or starting tilt angle of thevehicle produced by an inertial position (or attitude) sensor, and thiscalculated current actual tilt angle is compared with a threshold value,whereby this threshold value is produced dependent on the rotation ratesignal and in a form adapted to the respective vehicle type. In adisadvantageous manner, this method requires the use of a tilt sensorfor the determination of the initial or starting tilt of the vehicle.

Further ones of such evaluating methods are known from the DE 199 05 193and DE 199 05 379, which provide the evaluation of the rotation ratesignals through two independent channels, namely on the one hand throughevaluation of the differentiated rotation rate signals and throughevaluation of the integrated rotation rate signals on the other hand. Inthe latter named evaluation, the integrated rotation rate signals arecompared with a threshold value produced dependent on the rotation rate.

Whether a value pair, consisting of an integrated rotation rate signaland the associated rotation rate, is evaluated as a vehicle conditionleading to a tip-over, is determined or decided in connection with aprescribed vehicle-specific tip-over characteristic curve, which devicesthe arising value pairs into no-fire areas or regions (no triggering ofa safety device) and fire areas or regions (triggering of a safetydevice).

The methods described in DE 196 09 717 A1 and DE 197 44 083 A1 derivethe corresponding Cardanic angles from the rotation rates measured inall three axes of a vehicle, through integration, in order to determinetherefrom the position of a vehicle's center of gravity projected into ahorizontal plane and to signal a rollover of the vehicle if theprojected center of gravity exceeds the boundaries or limits of avehicle-fixed surface similarly projected into the horizontal plane.Furthermore, in this known method, the rotation energy of the vehicle isderived from the rotation rates, in order to recognize a tip-over thenwhen the rotation energy exceeds a certain threshold, which may, forexample, be that potential energy that is required for tilting ortipping the vehicle out of its momentary position (or attitude) into aposition (or attitude) in which the center of gravity reaches itsmaximum spacing distance relative to the roadway (or driving surface)plane.

The object of the invention consists in presenting a method for thetriggering of a safety device, which requires little data material forthe realization, and with which simultaneously tip-overs are timely andreliably recognizable.

This object is achieved by the characterizing features of the patentclaim 1. According to this, the rotation rate signals produced by arotation rate sensor with respect to a rotation axis are both low-passfiltered by means of a low-pass filter, with a limit frequency at whichthe signal components of the rotation rate signal characteristic for arollover process pass this low-pass filter un-filtered, as well as forthe production or generation of an integral value dependent on therotation rate of the vehicle, whereby a trigger signal for thetriggering of a safety device is then produced when the low-passfiltered rotation rate signal exceeds an adjustable trigger thresholdvalue that is produced dependent on the integral value. Preferably, thelimit frequency of the utilized low-pass filter is selected in such amanner that rapid tip-overs are recognized timely and safely or surely.In that regard, the limit frequency lies at a few Hz. This is achievedin an advantageous manner in that, through corresponding adjustment ofthe limit frequency of the utilized low-pass filter and the adjustmentof the trigger threshold value dependent on the integrated rotation ratesignal, a tip-over characteristic curve adapted to the vehicle isrealizable in such a manner that the value pairs coming intoconsideration for the low-pass filtered and the integrated rotation ratesignals are nearly unambiguously classifiable into no-fire regions andfire regions.

According to an advantageous further embodiment of the invention,besides the rotation rate of the vehicle, further vehiclecondition-specific parameters indicating the stability, especially thevertical acceleration, lateral acceleration, or the tilting of thevehicle, are detected by means of sensors, and the value of the triggerthreshold value is adapted, depending on at least one of theseparameters, to the stability condition of the vehicle indicated by thisparameter. If, for example, the transverse or lateral acceleration isused as a parameter, then the triggering shall occur earlier inconnection with a high acceleration value than for lower lateral ortransverse acceleration of the vehicle, which, with respect to thetip-over characteristic curve, means a shifting of the characteristicline or curve separating the no-fire region from the fire region. Themethod thereby becomes more sensitive with respect to the lateral ortransverse acceleration. If, contrary thereto, the vertical accelerationof the vehicle is to be used as a parameter, then the tip-overcharacteristic curve is similarly to be shifted to smaller values if theacceleration value significantly deviates from the value 1G, i.e.indicates a condition that tends toward weightlessness.

A further advantageous embodiment of the invention consists in providinga further low-pass filter for the filtering of the rotation rate signal,whereby its limit frequency is adjusted in such a manner so that thesignal components of the rotation rate signal that are characteristicfor a slow rollover process pass this further low-pass filterunfiltered, and thereafter only then are compared with a fixed triggerthreshold value when the integrated rotation rate signal reaches a fixedangle threshold value. Because this integrated rotation rate signalapproximately corresponds to the tilt angle of the vehicle, this anglethreshold value represents a minimum tilt angle. Only once this minimumtilt angle is reached, a comparison of the filtered rotation rate signalwith the fixed threshold value occurs, which fixed threshold valuepreferably represents a minimum rotation rate. Thereby a triggering of asafety device is also ensured for slow tip-overs—at the latest when thevehicle is lying on its side.

For the improvement of the triggering safety or security in all arisingtip-over scenarios, a third low-pass filtering of the rotation ratesignal can be carried out, whereby the limit frequency of the utilizedlow-pass filter lies between the value of the limit frequency of thefirst low-pass filter and the value of the limit frequency of the secondlow-pass filter.

For the further improvement of the triggering safety or security,according to an especially advantageous embodiment of the invention, thesensor signals of the further sensors indicating the stability of thevehicle can be utilized for the plausibilization, so that a triggeringis only made possible if all sensor signals actually allow an imminenttip-over to be recognized. Thus, preferably, the lateral acceleration ofthe vehicle, after a low-pass filtering, can be compared with aplausibility threshold, whereby a triggering is only permitted if thevalue of this lateral acceleration comprises a minimum value, wherebyespecially roll-over processes in the sand bed or with a curb impact aredetected.

Also the vertical acceleration of the vehicle can be utilized for theplausibilization, in that the trigger threshold value is adjusted sothat a triggering only occurs if the vertical acceleration significantlydeviates from the value 1G. Thereby, especially rollover processes ofthe screw or spiral ramp type or tip-overs over a cliff are detected, inwhich the vertical acceleration indicates weightlessness.

In the following, the inventive method shall be explained on the basisof example embodiments in connection with the drawings. It is shown by:

FIG. 1 a block circuit diagram for the carrying out of the inventivemethod,

FIG. 2 a tip-over characteristic curve in the representation of anω_(x)-∫ω_(x)dt-diagram for the explanation of the manner of operation orfunctioning of the arrangement according to FIG. 1,

FIG. 3 a further tip-over characteristic curve for the explanation ofthe manner of operation or functioning of the arrangement according toFIG. 1, and

FIG. 4 a block circuit diagram of a further example embodiment for thecarrying out of the inventive method.

In the figures, the same functional blocks or similarly operating partsare provided with the same reference characters. In that regard, theblock circuit diagrams are to be understood in such a manner that theillustrated functional blocks are realizable both with analog componentsas well as in a software manner, with respect to their function, bymeans of a processor. In the latter named case, the analog sensorsignals are digitalized before their processing, and are provided todigital filters, generally of first order, for the processing.

The block circuit diagram according to FIG. 1 shows a safety system withan arrangement for the carrying out of the inventive method. Thisarrangement consists initially of a rotation rate or gyro sensor B_(ω),which generates or produces a rotation rate signal proportional to theangular velocity ω_(x) (rotation rate) about the lengthwise orlongitudinal axis (x-axis) of a vehicle. The rotation rate signal isprovided or delivered to three low-pass filters TP_(ω1), TP_(ω2), andTP, as well as an integrator Int for the purpose of integration of therotation rate signal ω_(x).

Before the low-pass filtered rotation rate signals present at the outputof the low-pass filters TP_(ω1) and TP_(ω2) are subjected to a thresholdvalue comparison with respectively one comparator K_(ω1) or K_(ω2), anoffset- and offset-drift correction occurs, in that the rotation ratesignals filtered by the low-pass TP are subtracted by means of adders A1and A2 from the output signals of the low-pass filters TP_(ω1) andTP_(ω2). The low-pass filter TP utilized for the offset- andoffset-drift correction is of first order with a limit frequency f_(ω)of approximately 10 mHz.

The respective low-pass filtered and offset corrected rotation ratesignal are provided to the already mentioned comparators K_(ω1) andK_(ω2) via their non-inverting inputs, while a threshold valuegeneration circuit SW₁₁ or SW₁₂ is respectively connected to theinverting inputs thereof. For the generation of a corresponding triggerthreshold value, the integrated rotation rate signal ∫ω_(x)dt generatedby the integrator Int are provided to these threshold value generationcircuits SW₁₁ and SW₁₂.

The limit frequency f_(ω1) of the low-pass filter TP_(ω1) is selected sothat the signal components of the rotation rate signal ω_(x)characteristic for a rapid tip-over pass this low-pass filterunfiltered. The order of magnitude of this limit frequency in thatcontext lies at a few Hz.

The integral value ∫ω_(x)dt generated or produced by the integrator Intserves the threshold value generation circuit SW₁₁ for the establishmentof a trigger threshold value S_(ω1), which exists or is applied on theinverting input of the comparator K_(ω1). A vehicle-specific tip-overcharacteristic curve, as this is illustrated, for example, with anω_(x)-∫ω_(x)dt diagram according to FIG. 2, serves for the determinationof this trigger threshold value S_(ω1) dependent on the integral value∫ω_(x)dt. In that regard, ω_(x) represents the amount or value of therotation rate, i.e. the rotation speed of the rolling motion that arisesin connection with a threatening or impending tip-over of the vehiclewith respect to its x-axis, and ∫ω_(x)dt represents the value of theintegrated rotation rate signal, which corresponds essentially to thetilt angle of the vehicle in the y-direction (transverse or crosswiseaxis). The ω_(x)-∫ω_(x)dt graph of this diagram, which, contrary to thestraight lines illustrated in FIG. 2, can be realized as a multi-stagestep function, divides the (ω_(x), ∫ω_(x)dt) value pairs of the firstquadrant into two regions, which on the one hand relate to drivingconditions that shall lead to the triggering of a safety device, i.e.fire scenarios, and on the other hand represent no-fire scenarios ofwhich the (ω_(x), ∫ω_(x)dt) combinations are not allowed to lead totriggering of the safety device. The (ω_(limit), 0) combination or (0,α_(tip)) combination represents a boundary or limit condition of avehicle with a rotation rate ω_(limit) in the x-direction and a tiltangle of 0° or with a rotation a rotation rate 0 and a tilt angle(static tip angle) α_(tip), which leads to a tip-over. These parametersare vehicle-specific and must therefore be determined separately foreach vehicle type.

For a certain or particular Veldt value produced by the integrator Int,designated as α^(*) in FIG. 2, the associated ω_(x) value is determinedby means of the ω_(x)-∫ω_(x)dt graph according to FIG. 2, which ω_(x)value is provided as the trigger threshold value S_(ω1) to thecomparator K_(ω1). If the value produced by the low-pass filter TP_(ω1)exceeds this trigger threshold value S_(ω1), then a trigger signal isoutput via an OR-gate G to a safety device.

In contrast, the trigger threshold value S_(ω2) output from thethreshold value generation circuit SW₁₂ to the comparator K_(ω2) isprescribed as a fixed value and arises from the ω_(x)-∫ω_(x)dt diagramaccording to FIG. 3. According to this, a triggering shall occur afterreaching of a minimum rotation rate ω_(min) an of the vehicle only if acertain ∫ω_(x)dt value is produced, i.e. the vehicle comprises a certainminimum tilt angle α_(limit). In that regard, the minimum rotation rateω_(min) is dependent on the frequency content of the rotation ratesignal, and therewith on the limit frequency of the utilized low-passfilter TP_(ω2). In that regard, the allot value is adjusted so that atriggering of the safety device occurs for slow tip-over processes atthe latest when the vehicle is lying on its side, while a triggering isomitted upon driving into a steep wall which generally does not comprise90°.

Besides the gyro sensor B_(ω), the arrangement according to FIG. 1comprises a further sensor B_(ay) that detects the lateral or transverseacceleration of the vehicle. The acceleration signal a_(y) of thefurther sensor B_(ay) is first provided to a low-pass filter TP_(y), ofwhich the limit frequency f_(y) is adjusted in such a manner in order toprovide the signal components characteristic for a transverseacceleration unfiltered to the non-inverting input of a comparator K_(y)for the purpose of comparison with a threshold value S_(y), whereby theoutput of this comparator K_(y) is connected with the threshold valuegeneration circuit SW₁₁. The threshold value S_(y) is output from athreshold value generation circuit SW₂₁ to the inverting input of thecomparator K_(y) and corresponds to a certain value or magnitude of thetransverse acceleration. If this threshold value S_(y) is exceeded bythe filtered acceleration signal, the level change that is triggeredthereby causes the tip-over characteristic curve according to FIG. 2that is used for the outputting of the trigger threshold value S_(ω1) tobe shifted toward smaller values. Thereby the arrangement becomes moresensitive with respect to high transverse accelerations of the vehicle,and a shorter reaction time from the time point of the detection of animpending tip-over until the triggering of the safety device is ensured.

Instead of the acceleration sensor B_(ay) measuring the transverseacceleration, an acceleration sensor B_(az) measuring the verticalacceleration of the vehicle can also be used, of which the signals aresimilarly filtered by means of a low-pass filter TP_(z) and arecompared, by means of a comparator K_(z), with a threshold value S_(z)generated by a threshold value generation circuit SW₃₁, whereby, uponthe exceeding of this threshold value by the filtered accelerationsignal, the corresponding level change similarly is provided to thethreshold value generation circuit SW₁₁. The FIG. 1 shows thesecomponents B_(az), TP_(z), K_(z) and SW₃₁ as well as the connectionlines in a dashed line illustration.

Through a level change effectuated by the comparator K_(z), thethreshold value generation circuit SW₁₁, is similarly caused to outputtrigger threshold values S_(ω1) shifted to smaller values. For thedetermination of the threshold value S_(Z) to be output by the thresholdvalue generation circuit SW₃₁, one proceeds from the consideration thata stable vehicle condition is present if the value of the accelerationsignal output by the acceleration sensor B_(az) amounts to at least 1G(=earth's gravitational acceleration). In such a condition, noadaptation of the trigger threshold value S_(ω1) is necessary. Contrarythereto, for low a_(z) values, one must proceed from a less-stabledriving condition of the vehicle, with the result that now an adaptationof the trigger threshold value S_(ω1) must be carried out in such amanner that with corresponding ω₁ values a triggering must occur earlierthan for a stable vehicle position (or attitude). These considerationsmust be taken into account in the setting or specifying of thethresholds S_(z) for the threshold value generation circuit SW₃₁.

In the arrangement according to FIG. 1 for the carrying out of theinventive method, naturally the acceleration sensor B_(y) for thedetection of the transverse acceleration a_(y) as well as theacceleration sensor B_(z) for the detection of the vertical accelerationcan be simultaneously utilized, in order to ensure an optimum dynamicadaptation of the trigger threshold S_(ω1). In this case, the outputs ofthe two comparators K_(y) and K_(z) are separately connected via aseparate line respectively with the threshold value generation circuitSW₁₁ (illustrated in the FIG. 1 by two parallel dashed-representedlines).

The arrangement according to FIG. 4 differs relative to that accordingto FIG. 1 initially by the number of the low-pass filters provided forthe evaluation of the rotation rate ω_(x) output by the rotation ratesensor B_(ω), and of the corresponding following or downstream-connectedcomparators with associated threshold value generation circuits. Besidesthe low-pass filter TP_(ω1), further low-pass filters TP_(ω2) andTP_(ω3) are utilized, whereby the low-pass filter TP_(ω2) corresponds tothe low-pass filter TP_(ω2) of FIG. 1 with respect to its function andlayout or design, i.e. is provided for the detection of slow tip-overs.Respectively one comparator K_(ω1), K_(ω2) and K_(ω3) with associatedthreshold value generation circuits SW₁₁, SW₁₂ and SW₁₃ iscircuit-connected after each one of the three low-pass filters TP_(ω1),TP_(ω2) and TP_(ω3) whereby these threshold value generation circuitsrespectively output a trigger threshold value SW_(ω1), SW_(ω2) orSW_(ω3). The outputs of the three comparators K_(ω1), K_(ω2) and K_(ω3)are similarly guided or lead to an OR-gate G₁, which in turn actuates anAND-gate G₂ and an AND-gate G₃ with respectively two inputs. The signalsoutput by the low-pass filters TP_(ω1), TP_(ω2) and TP_(ω3) aresubjected to an offset- and offset-drift correction similarly as shownin FIG. 1, in that the signal output by the low-pass filter TP issubtracted from these by means of adders A₁ to A₃.

As already described above, the limit frequency f_(ω2) as well as thetrigger threshold value S_(ω2) output by the threshold value generationcircuit SW₁₂ is adjusted as for the low-pass filter TP_(ω2) or thethreshold value generation circuit SW₁₂ according to FIG. 1. Now, thelimit frequency f_(ω3) of the additional low-pass filter TP_(ω3) isadjusted so that the value thereof lies between the value of the limitfrequency f_(ω1) of the first low-pass filter TP_(ω1) and the value ofthe limit frequency f_(ω3) of the second low-pass filter TP_(ω2). Thecontrolling or determinative threshold values α_(limit) and ω_(min) (astrigger threshold value S_(ω3)) that are to be adjusted by the thresholdvalue generation circuit SW₁₃ similarly lie somewhat lower than thevalues utilized in the arrangement according to FIG. 1.

In a corresponding manner, also for the evaluation of the accelerationsignals of the acceleration sensor B_(ay) for the transverse directionand of the acceleration sensor B_(az) for the vertical direction,respectively not only one single low-pass filter, but ratherrespectively two low-pass filters TP_(y1) and TP_(y2) or respectivelyTP_(z1) and TP_(z2) are utilized. Also respectively one comparatorK_(y1) and K_(y2) or respectively K_(z1) and K_(z2) with associatedthreshold value generation circuits SW₂₁ and SW₂₂ or respectively SW₃₁and SW₃₂ are circuit-connected after these low-pass filters, whereby thementioned threshold value generation circuits output threshold valuesS_(y1) and S_(y2) or respectively S_(z1) and S_(z2).

The outputs of the comparators K_(y1) and K_(y2) are provided viaseparate lines to respectively one input of the threshold valuegeneration circuit SW_(ω1), so that a dynamic threshold value adaptationcan be carried out as in the arrangement according to FIG. 1, wherebywith acceleration values indicating unstable driving conditions of thevehicle lead to the reduction of the trigger threshold values S_(ω1),thus triggering is effectuated already at small ω_(x) values.

The limit frequencies f_(y1) and f_(y2) of the low-pass filters TP_(y1)and TP_(y2) are adjusted so that the first low-pass filter TP_(y1)comprises a high limit frequency f_(y1) and the second low-pass filterTP_(y2) comprises a low limit frequency f_(y2). The same applies to thethreshold values S_(y1) and S_(y2) produced by the threshold valuegeneration circuits SW₂₁ and SW₂₂.

For the plausibilization of the rotation rate signals ω_(x) possiblyleading to the triggering, the outputs of the comparators K_(y1) andK_(y2) are additionally provided via an OR-gate G₅ to the second inputof the AND-gate G₂, so that a triggering is permitted only when thetransverse acceleration comprises a minimum value |y| throughcorresponding adjustment of the threshold values S_(y1) and S_(y2),whereby especially rollover processes in the sand bed or rolloverprocesses caused by a curb impact are detected.

Thus, a triggering via a further OR-gate G₄ occurs only when both theOR-gate G₁ transmits or conducts-further a trigger signal as well as atleast one of the comparators K_(y1) or K_(y2) produces a high level.

The evaluated acceleration signals of the acceleration sensor B_(az)similarly serve for the plausibilization of the rotation rate signalsω_(x) possibly leading to the triggering, in that the outputs of thecomparators K_(z1) and K_(z2) are provided via an OR-gate G₆ to the oneinput of the AND-gate G₃, and the second input thereof is connected withthe output of the OR-gate G₁. For the fulfillment of this purpose, thelimit frequencies f_(z1) and f_(z2) of the low-pass filters TP_(z1) andTP_(z2) as well as the threshold values S_(z1) and S_(z2) to be preparedby the threshold value generation circuits SW₃₁ and SW₃₂ are adjusted sothat a triggering is only permitted when the acceleration in verticaldirection significantly deviates from the value 1G (=earth'sgravitational acceleration), whereby especially rollover processes ofthe screw or spiral ramp type (a_(z) greater than 1G), for which atriggering shall occur already in the upward movement, or a tip-overover a cliff, in which the a_(z) value indicates approximatelyweightlessness, are detected.

Also the limit frequencies f_(z1) and f_(z2) of the low-pass filtersTP_(z1) and TP_(z2) are adjusted so that the first low-pass filterTP_(z1) comprises a high limit frequency f_(z1) and the second low-passfilter TP_(z2) comprises a low limit frequency f_(z2). The same appliesto the threshold values S_(z1) and S_(z2) generated by the thresholdvalue generation circuits SW₃₁ and SW₃₂.

Finally, the evaluated acceleration signals a_(z) of the accelerationsensor B_(az)—as is also realizable in the arrangement according to FIG.1—can be used for the dynamic adaptation of the trigger threshold valuesS_(ω1), in that the outputs of the comparators K_(z1) and K_(z1) areprovided via separate lines to separate inputs of the threshold valuegeneration circuit SW_(ω1), as this is shown in FIG. 4 with dashedconnecting lines V. Thereby the trigger threshold value S_(ω1) isadjusted dependent on the output values of the comparators K_(y1),K_(y2), K_(z1) and K_(z2).

Moreover, it should be mentioned that the number of the utilizedlow-pass filters for the evaluation of the acceleration signals does notneed to remain limited to two. If, for example, respectively a thirdlow-pass filter is used for the evaluation of the acceleration signalsa_(y) and a_(z), then the limit frequencies thereof are adjusted in sucha manner so that the first low-pass filter comprises the highest limitfrequency and the third low-pass filter comprises the lowest limitfrequency in a diminishing succession. The same applies to the thresholdvalues.

1. Method for the triggering of a safety device in a motor vehicle in arollover process by means of a rotation rate sensor (B_(ω)), in whichthe rotation rate signals (ω_(x)) generated by the rotation rate sensor(B_(ω)) are evaluated for the recognition of the rollover process, andthe following method steps are carried out: a) low-pass filtering of therotation rate signals (ω_(x)) by means of a low-pass filter (TP_(ω1))with a limit frequency (f_(ω1)), in which the signal components of therotation rate signal (ω_(x)) characteristic for a rollover process passthis low-pass filter (TP_(ω1)) unfiltered and thereafter are provided toa threshold value comparison with an adjustable trigger threshold value(S_(ω1)) b) integration of the rotation rate signals (ω_(x)) for thegeneration of an integral value (∫ω_(x)dt) dependent on the rotationrate of the motor vehicle, c) generation of the trigger threshold value(S_(ω1)) dependent on the integral value (∫ω_(x)dt), and d) generationof a trigger signal for the triggering of the safety device uponexceeding of the trigger threshold value (S_(ω1)) by the low-passfiltered rotation rate signal.
 2. Method according to claim 1, wherein,besides the rotation rate signals (ω_(x)) of the rotation rate sensor(B_(ω)), signals (a_(y), a_(z)) of further sensors (B_(y), B_(z)) areprocessed, whereby the further sensors (B_(y), B_(z)) detectdriving-condition specific parameters indicating the stability of themotor vehicle, especially vertical acceleration (a_(z)), lateralacceleration (a_(y)) and tilt angle (α), and the value of the triggerthreshold value (S_(ω1)) is adapted dependent on at least one of theseparameters, in that the trigger threshold value (S_(ω1)) is increased ordecreased corresponding to the degree of the stability of the motorvehicle indicated by the signals of the further sensors (B_(y), B_(z)).3. Method according to claim 2, wherein the lateral acceleration of themotor vehicle is detected by means of an acceleration sensor (B_(y)). 4.Method according to claim 2, wherein the vertical acceleration of themotor vehicle is detected by means of an acceleration sensor (B_(z)).5-10. (canceled)
 11. Method according to claim 1, wherein a) a secondlow-pass filtering of the rotation rate signals (ω_(x)) is carried outby means of a second low-pass filter (TP₂) with a limit frequency(f_(ω2)), wherein the signal components of the rotation rate signal(ω_(z)) characteristic for a slow rollover process pass the secondlow-pass filter (TP_(ω2)) unfiltered, and thereafter are compared with asecond threshold value (S_(ω2)), when the integrated rotation ratesignal (∫ω_(x)dt) has reached a first angle threshold value (α_(limit)),and b) the safety device is triggered upon exceeding of the secondthreshold value (S_(ω2)) by the low-pass filtered rotation rate signal.12. Method according to claim 11, wherein the second threshold value(S_(ω2)) corresponds to the value of a minimum rotation rate (ω_(min))13. Method according to claim 11, wherein a) a third low-pass filteringof the rotation rate signals (ω_(x)) is carried out by means of a thirdlow-pass filter (TP_(ω3)) with a limit frequency (f_(ω3)), of which thevalue lies between the value of the limit frequency (f_(ω1)) of thefirst low-pass filter (TP_(ω1)) and the value of the limit frequency(f_(ω2)) of the second low-pass filter (TP_(ω2)), and thereafter thesignal components of the rotation rate signals that pass through thethird low-pass filter are compared with a third threshold value(S_(ω2)), when the integrated rotation rate signal (∫ω_(x)dt) hasreached a second angle threshold value (S_(α2)), and b) the safetydevice is triggered upon exceeding of the third threshold value (S_(ω3))by the low-pass filtered rotation rate signal.
 14. Method according toclaim 13, wherein the third threshold value (S_(ω3)) lies between thevalue of the first threshold value (S_(ω1)) and the value of the secondthreshold value (S_(ω2)).
 15. Method according to claim 2, wherein thelateral acceleration (a_(y)) detected by means of the accelerationsensor (B_(y)), after a low-pass filtering by means of at least onelow-pass filter (TP_(y1)), is compared with a plausibility threshold(S_(y1), S_(y2)), whereby a triggering is possible only when the valueof the low-pass filtered acceleration signal exceeds this plausibilitythreshold (S_(y1), S_(y2)).
 16. Method according to claim 2, wherein thevertical acceleration (a_(z)) detected by means of the accelerationsensor (B_(z)), after a low-pass filtering by means of at least onelow-pass filter (TP_(z1), TP_(z2)), is compared with the accelerationvalue of 1G, whereby a triggering is possible only when the value of thelow-pass filtered acceleration signal essentially deviates from thisvalue.